JPH0459836A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To obtain the title film having excellent surface characteristics, smoothness and fixing property and useful as a magnetic recording medium, packaging material and building material, etc., by providing a water soluble or water- dispersible resin layer containing paterite type calcium carbonate grains on the surface of a polyester film. CONSTITUTION:The objective film in which a water soluble and/or water dispersible resin layer containing paterite type calcium carbonate grains (preferably having 0.1-10mum average grain diameter and <=1.40 distribution value of grain size), preferably at an amount of 30-40wt.% is provided on at least one side of a polyester film, preferably at a thickness of 0.02-1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to polyester films with improved surface properties and slipperiness.

[Prior art and problems to be solved by the invention] Two-wheel stretched polyester films, especially two-wheel stretched polyethylene terephthalate films, have excellent transparency, dimensional stability, mechanical properties, electrical properties, gas barrier properties, heat resistance, and chemical resistance. Packaging materials, electrical insulating materials, photosensitive materials that use silver salts, diazo compounds, photosensitive resins, etc., drawing materials,
It is used as a base material for electrophotographic materials, magnetic recording materials, etc.

Recently, as magnetic recording materials have become more dense and capacitors have become more capacitive, the polyester films used have become increasingly flat and have good slipperiness.
That is, a material having smoothness is required. The need for smooth films is also increasing in many other applications, such as optical and electrophotographic applications.

However, polyester films with high smoothness have very poor sliding properties between films, which may cause surface defects such as blocking and scratches, and may cause deterioration in winding performance and appearance.
Furthermore, it is known to cause deterioration of workability during processing.

Conventional methods for improving the slipperiness of polyester films include adding fine organic or inorganic particles to the polyester film (additional particle method), and precipitating transesterification catalyst residue during polyester polymerization. (precipitated particle method), polymer blend method,
There are methods for improving polyester compositions, such as adding organic lubricants.

However, in the methods using these compositions, the reality is that if one of the slipperiness and flatness is improved, it is difficult to simultaneously improve the other one. Further, the improvement method using a composition has a limit in optical applications requiring transparency. The method of blending an organic lubricant can achieve a certain degree of smoothness by using a suitable amount of inorganic particles, but it may cause contamination of equipment or products due to lubricant transfer, and high vacuum during the vapor deposition process. There are many problems, such as difficulty in achieving and maintaining the degree of protection, and decreased adhesion between the eyebrows when used as a laminate.

There is a method to achieve smoothness by laminating a layer containing the composition with a flat layer by co-extrusion, but there are problems with using the composition mentioned above, as well as shape transfer of the composition to the flat layer. There is a problem.

There is also a method of stretching a film that has been surface-treated by solvent treatment, corona discharge treatment, etc. to form protrusions on the surface, but there are various restrictions on the shape of the protrusions, and the slipperiness is often insufficient.

In contrast to these methods, a method in which a coating layer is provided and minute and secret protrusions are formed in the coating layer is attracting attention as a method for smoothing the film. As a method for forming protrusions on the coating layer,
A method of incorporating inorganic particles into the coating layer has been proposed.

Silicon oxide, calcium carbonate, aluminum oxide, barium sulfate, titanium dioxide, etc. are known as inorganic particles used in the above method, but since these particles usually have a wide particle size distribution, they may cause variations in the physical properties of the film. Further, problems such as a decrease in smoothness due to the formation of coarse protrusions and drop-off of the protrusions have occurred.

A method of incorporating monodisperse particles with a narrow particle size distribution into the coating layer is effective in solving the above problems, and a method using silicon oxide particles with a narrow particle size distribution such as silica sol or monodisperse silica has been proposed. There is. However, since such particles have a fine particle size, they need to be added in large quantities to develop slipperiness, which tends to cause a decrease in transparency and easy adhesion.Also, silicon oxide particles have high hardness, so they cannot be easily added to the surface. The exposed silicon oxide particles may damage the back side of the rolled product, resulting in product shortages.

On the other hand, although calcium carbonate particles are effective as slipperiness improving particles due to their low hardness, conventionally known particles have a wide particle size distribution and cannot be put to practical use. Furthermore, in order to narrow the particle size distribution, pulverization and classification treatments are performed, but in order to obtain the desired particle size distribution, repeated classification operations are required many times, which is not practical.

[Means to solve the problem]

In view of the above-mentioned problems, as a result of intensive studies, the present inventor found that a laminated polyester film having a resin layer containing certain specific calcium carbonate particles has excellent properties, and was able to complete the present invention. .

In other words, the gist of the present invention is a laminated film having a small amount of polyester film (both having a water-soluble and/or water-dispersible resin layer on one side, and containing vaterite-type calcium carbonate particles in the resin layer). A laminated polyester film characterized by:

The present invention will be explained in detail below.

The polyester of the polyester film in the present invention refers to polyethylene terephthalate in which 80 mol% or more of its constituent units are ethylene terephthalate, or polyethylene naphthalate in which 80 mol% or more of its constituent units are ethylene naphthalate, or its constituent units. is poly-1,4-cyclohexane dimethylene terephthalate in which 80 mol% or more of the Examples of copolymerization components other than these components include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, and polytetramethylene glycol, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and 5-sodiosulfoisophthalate. acid ζ adipic acid,
Dicarboxylic acid components such as azelaic acid, sebacic acid and their ester-forming derivatives, oxymonocarboxylic acids such as oxybenzoic acid and its ester-forming derivatives, and the like can be used.

In the composition of the polyester film constituting the base of the film of the present invention, additive particles, precipitated particles, other catalyst residues that form protrusions on the film surface, and resins other than polyethylene terephthalate are used for optical purposes requiring transparency, etc. In applications such as high-density magnetic recording materials in which vapor-deposited metal is used as a magnetic layer, it is preferable to reduce the amount as much as possible, but depending on the application, it may be contained in an amount commonly used by those skilled in the art.

That is, the film of the present invention may contain antistatic agents, stabilizers, lubricants,
A crosslinking agent, an antiblocking agent, an antioxidant, a coloring agent, a light blocking agent, an ultraviolet absorber, and the like may be included.

The laminated film of the present invention is a film made of such polyester provided with a water-soluble and/or water-dispersible resin layer containing vaterite-type calcium carbonate particles.

The water-soluble or water-dispersible resin in the present invention functions as a binder that binds vaterite-type calcium carbonate to each other and binds the coating layer and the polyester of the base, and even if it is a polymer compound. The coating material may be a low-molecular compound, and the coating material can be selected depending on the purpose as long as it does not interfere with the properties of the base film of the present invention.

For example, thermoplastic resins, thermosetting resins, or compositions in which they are combined with antistatic agents, lubricants, surfactants, particles, etc. can be used as needed.

More specifically, the thermoplastic resins include polyester resins, condensation polymerization resins such as polyurethane resins, acrylic resins such as vinyl acetate resins, polyolefin resins, vinyl chloride resins, vinylidene chloride resins, polystyrene resins, SBR, etc. N.B.
Addition polymerization resins such as rubber resins such as R: polyvinyl alcohol polyvinylpyrrolidone, cellulose, gelatin,
Water-soluble resins such as glue; thermosetting resins include, but are not limited to, epoxy resins, melamine resins, urea resins, phenol resins, silicone resins, and copolymers of multiple resins. or a mixture of a plurality of resins.

The resin layer of the present invention may contain appropriate amounts of various additives such as dyes, pigments, lubricants, antioxidants, ultraviolet absorbers, antistatic agents, and surfactants depending on the use.

Methods for forming the above-mentioned resin layer on a polyester film include a reverse roll coater, a Clavia coater, a rod coater, an air doctor coater, or other coating equipment as shown in "Coating Method" by Yuji Harasaki, published by Maki Shoten, 1979. An aqueous solution or aqueous dispersion of the resin may be applied to a film that has already been formed using a film (or the application may be performed during the film manufacturing process).

For example, when providing a resin layer on a two-wheel stretched polyester film, an aqueous solution or aqueous dispersion of the resin is applied to the single-wheel stretched film in the longitudinal direction, stretched in the transverse direction in a dry or undried state, and immediately heat-treated. This method is particularly preferably adopted because film formation, coating, and drying can be performed at the same time, which has a great advantage in terms of manufacturing costs.

The resin layer can be provided on one side or both sides, and
When provided on both sides, the resin layers may be the same or different. In order to improve the applicability and adhesion of the resin to the film, the film may be subjected to chemical treatment or electrical discharge treatment before coating. It's okay.

Further, in order to improve the adhesion to the resin layer of the laminated polyester film of the present invention, coating properties, etc., the resin layer may be subjected to a discharge treatment after the resin layer is formed.

In the polyester film of the present invention obtained as described above, the thickness of the polyester film is preferably in the range of 1 to 500 μm, and the thickness of the resin layer is 0.01 μm.
The range is preferably 5 μm, more preferably 0.02 μm.
~lam range.

If the thickness of the resin layer is less than 0.01 μm, it is difficult to obtain a uniform resin layer, and the product is likely to have uneven coating. If it is thicker than 5 μm, the slipperiness decreases, making it difficult to handle the film, which is undesirable.

One of the features of the present invention is that the resin layer contains specific vaterite-type calcium carbonate particles. Calcium carbonate particles can be produced by pulverizing and classifying natural calcium carbonate, as well as by, for example, Japanese Patent Application Laid-Open No. 59-69.
As disclosed in Japanese Patent No. 425, precipitated calcium carbonate is produced by a so-called synthesis method in which a carbon dioxide-containing gas is injected into a calcium hydroxide solution and reacted.

In this case, calcite-type calcium carbonate particles having a relatively uniform particle size are obtained, but the particle size distribution of the particles does not allow the object of the present invention to be achieved.

The present inventors have discovered that in such a synthesis method, vaterite-type calcium carbonate particles with an extremely sharp particle size distribution can be produced by selecting production conditions such as the hydrogen ion concentration in the system and the reaction rate. Although such vaterite-type calcium carbonate particles can be blended into the resin as is, it is preferable to perform a surface treatment to improve the dispersion stability in the resin.As a surface treatment agent that also serves as a dispersant, , for example, JP-A-59-694
Preferably used are surface treating agents such as those described in JP-A No. 26 or JP-A-1-256558, particularly high-molecular polycarboxylic acids or their sodium salts and ammonium salts.

These are usually effective when added during the manufacturing stage of the particles.

Such vaterite-type calcium carbonate is obtained in the form of a sphere or an ellipsoid, and the ratio of the major axis to the minor axis is usually 1.8.
It can be used depending on the purpose.

In the present invention, the particle size distribution value of the vaterite-type calcium carbonate defined below is usually 1.60 or less, preferably 1.50 or less, more preferably 1.40 or less. If this value exceeds 1.60, the surface roughness of the final film will be non-uniform and cannot be put to practical use.

Further, the average particle size of the particles used in the present invention is usually 0, 0
5-1.5 am, preferably 0.1-1.0 am
is within the range of If particles having this value of less than 0.05 pm are used, no effect of improving the slipperiness of the film can be expected.

On the other hand, when particles exceeding 1.5 μm are used, the dispersion stability of the particles deteriorates, and the properties of the obtained film are also inferior.

In the present invention, the content of the particles in the resin layer is usually 1
It ranges from % to 60% by weight, preferably 3% by weight.
-40% by weight. If the content is less than 1% by weight, no improvement in slipperiness can be expected; on the other hand, if the content exceeds 60% by weight, the strength of the resin layer will decrease, causing peeling from the base polyester film or particles falling off. It begins to occur.

In the present invention, vaterite-type calcium carbonate particles are used to improve slipperiness and adhesion, and to control surface roughness, but inorganic and organic particles may also be used as additives depending on the properties to be imparted to the film. I can't help it.

〔Example〕

The present invention will be described below with reference to examples, but the present invention is not limited by the following examples unless it exceeds the gist thereof.

Note that the evaluation method in the examples was as follows.

(1) Average particle size and particle size distribution value The particle size was measured by photography using an electron microscope and converted into equivalent spheres. For particle size distribution, the particle sizes of about 1000 particles were measured, and the volumes were integrated from the large particle side. The particle size corresponding to 25% of the total volume is d□, and the particle size corresponding to 75% is d'F.
The sharpness of the particle size distribution is indicated by the value of the ratio (d zs/d7.) as s.The closer this value is to 1, the sharper the particle size distribution.The average particle diameter is expressed as d, (μm).

(2) Easy sliding property The friction coefficient between the resin layer surface of the film and the opposite surface of the resin layer was measured according to ABTM-D-1894-63. did.

(3) Adhesiveness (blocking property) 40℃, 80% RH110 by heat pressing in a constant temperature and humidity chamber
kg/cm” for 20 hours, A
Peel strength was measured according to the method of BTM-D-1893, and the 0 criteria were O: good, Δ: slightly poor, and ×: poor.

(4) Smoothness Measured with a thin film step needle ET-10 manufactured by Small Plate Research Institute with a stylus tip radius of 0.58 m and a stylus load of 1 g, and judged as 0 based on the height from the base to the top of the protrusion. Standards are O: good, Δ
: Slightly inferior, ×: Defective.

(5) Transparency The turbidity of the film was measured according to JIS K6714 using a sphere-splitting turbidimeter NDH-20D manufactured by Nippon Heavy Industries, Ltd.

The evaluation criteria were ○: good, Δ: slightly poor, and ×: poor.

(6) Paint film strength Scotch's "Tape Cleaning Fabr"
Wrap the IC''' in silicone rubber and attach it to Taihei Rika Kogyo Co., Ltd.'s Rubbing Te5ter.
The surface of the resin layer was rubbed back and forth 10 times using Tape Cleaning Fabric, and the degree of peeling of the resin layer was visually determined. The load applied during friction was 350 g/cm'', and the 6 criteria were O: good, Δ: slightly poor, and X: poor.

(7) Adhesiveness ■ Magnetic layer Apply magnetic paint to the resin layer surface of the adhesive film and heat it at 80°C for 1 hour.
It was dried for a minute and then aged at 80° C. for 24 hours to obtain a magnetic recording medium having a magnetic layer of about 5 μm. after that,
A double-sided adhesive tape is pasted on a stainless steel plate with a thickness of 1 mm, a magnetic recording medium is pasted on top of the tape so that the magnetic layer surface of the magnetic recording medium is in contact with the adhesive tape, and a polyester film is placed at an angle of 180 @ from the magnetic layer. Peeling resistance during peeling was measured using a tensile tester at a speed of 500 mm/min. The magnetic paint for the magnetic layer consists of 50 parts of polyurethane, 20 parts of nitrocellulose, 30 parts of vinyl chloride-vinyl acetate resin, 7.5 parts of isocyanate compound, 12 parts of carbon black, 4 parts of lecithin, and 460 parts of r-FetOs. A mixture of equal amounts of ethyl ketone, toluene, and methyl isobutyl ketone dispersed in 900 parts of a solvent was used.

■Printing ink adhesiveness Screen ink “FDSS2” manufactured by Toyo Ink Mfg. Co., Ltd.
1 391 Indigo" and "Reducer-P" were mixed at a ratio of 10:1, and this was applied to the resin layer surface of the film to a thickness of about 10 μm using a 300 mesh silk screen, and the Ushio Inc. UV Irradiation device “UVC-402
/IHN:302/IMN", mercury lamp output 160
The ink was cured at W/cm, line speed of 5 m/min, and rump film interval of 100 mm.

After curing, apply cellophane tape (18 mm width) manufactured by Nichiban Co., Ltd. to a length of 7 cm to prevent air bubbles from forming on the ink-coated surface of the film, and then apply a constant load to the film using a 3 kg manual load roll. was fixed, one end of the cellophane tape was connected to a 500 g weight, and the weight was allowed to fall naturally over a distance of 45 cm, after which a peel test in a 180° direction was started.

The evaluation criteria for adhesion are as follows for both the above and (1).

○: The resin layer does not peel off at all.

Δ: The resin layer peels off a little.

xf The resin layer is almost peeled off.

Comparative example! Polyethylene terephthalate having an intrinsic viscosity of 0.62 and containing almost no surface protrusion forming agent based on polymerization catalyst residue etc. was melted at about 285°C and extruded onto a cooling drum at about 60°C while applying electrostatic charge. Further, it was stretched by 3.5 times in the machine direction at 83°C with rolls, and then stretched in the transverse direction at 110°C.
Heat treated at 220°C to a thickness of 121. Two-wheel stretched films with cr, m, and surface roughness (Ra) of 50 people were obtained. This film had extremely poor windability, making it difficult to obtain a long film roll, and the resulting film roll had a poor winding appearance, making it impossible to put it to practical use. Just to be safe, I cut it out as an A4 size sheet and observed the workability, but the films stuck together and became one whole, making it difficult to handle the film. The coefficient of friction of this film could not be measured because the film did not slip.
The obtained results are shown in Table 1 along with the results of other examples and comparative examples.
Shown below.

Comparative Example 2 Hytran AP-40 (trade name) from Dainippon Ink & Chemicals Co., Ltd., which is a polyurethane water dispersion, 80 parts (solid weight, the same applies hereinafter), and Dainippon Ink & Chemicals Co., Ltd., which is a polyester water dispersion. ) Finetex B5-670
(Product name) A coating solution consisting of 20 parts was applied to one side of the film of Comparative Example 1 after longitudinal stretching and before transverse stretching, and then
In the same manner as above, a two-wheel stretched polyester film having a resin layer thickness of 0.20 part m was obtained. Although the obtained laminated film has excellent adhesion to the magnetic layer and printing ink,
Like Comparative Example 1, the slipperiness was poor and it could not be put to practical use.

Example 1 5 parts of VAN-030 (manufactured by Maruo Calcium Co., Ltd.), which is vaterite type calcium carbonate particles surface-treated with a high molecular weight polycarboxylic acid having an average particle diameter of 0.25 #m and a particle size distribution value of 1.29. , Hytran AP-40 (trade name) from Dainippon Ink & Chemicals Co., Ltd., which is a polyurethane water dispersion.
75 parts, Finetex ES-670 (trade name) from Dainippon Ink and Chemicals Co., Ltd., which is a polyester aqueous dispersion
A two-wheel stretched polyester film having a resin layer thickness of 0.20 μm was obtained in the same manner as in Comparative Example 2 except that a coating agent of 20 parts was applied. The properties of the obtained laminated film were excellent in slipperiness, adhesion, smoothness, transparency, and coating strength, as well as excellent adhesion to the magnetic layer and TRV ink.

Example 2.3.4.5 A two-wheel stretched polyester film was prepared in the same manner as in Example 1, except that the particle size of vaterite-type calcium carbonate, the blending ratio in the coating agent, and the coating layer thickness were changed as shown in Table 1. Obtained.

All of the obtained films were excellent in slipperiness, adhesion, smoothness, transparency, and coating strength.

Example 6 5 parts of the vaterite type calcium carbonate particles used in Example 1, Nippon Acrylic Chemical (a polyacrylate water dispersion)
A two-wheel stretched polyester film was obtained in the same manner as in Example 1, except that a coating agent consisting of 895 parts of Primal HA-89 manufactured by Co., Ltd. was applied.

The obtained film has properties such as slipperiness, adhesion, smoothness, transparency,
It had excellent coating strength and adhesion to the magnetic layer and printing ink.

Comparative Example 3 In place of the vaterite-type calcium carbonate particles of Example 1, calcite-type calcium carbonate surface-treated with a high-molecular polycarboxylic acid having an average particle size of 0.25 parts m and a particle size distribution value of 1.99 is used. A two-wheel stretched polyester film was obtained in the same manner as in Example 1 except for this. Although the obtained laminated film had excellent slipperiness and adhesion properties due to the coarse particles contained in the calcite-type calcium carbonate, it was found that the smoothness and transparency were adversely affected. When observing the surface of the resin layer, it was observed that coarse particles had fallen off, which also affected the smoothness and
This is thought to be one of the reasons for the decline in transparency.

〔Effect of the invention〕

Claims (1)

[Claims] (1) A laminated polyester film having a water-soluble and/or water-dispersible resin layer on at least one side of the polyester film, the resin layer containing vaterite-type calcium carbonate particles.